I think it's describing a particular lexer or preprocessor bug that GCC never had, so "a + = 1" should have been a syntax error in C89 as well. Someone mirror

I think it's describing a particular lexer or preprocessor bug that GCC never had, so "a + = 1" should have been a syntax error in C89 as well. Someone mirrored GCC 0.9 (1987), the relevant bits start here: https://github.com/huangguiyang/gcc-0.9/blob/a83ea1b45dc3187d9fc4f7a3d8091c1454991afe/parse.y#L1296 https://github.com/huangguiyang/gcc-0.9/blob/a83ea1b45dc3187... // Read the next non-whitespace character. 1296: c = skip_white_space(); // Match it against '+' 1618: case '+': // Tentatively give it the token 'PLUS_EXPR' 1637: case '+': 1638: yylval.code = PLUS_EXPR; break; // Read the next character, but note that whitespaces are NOT skipped here. 1663: c1 = getc(finput); // Match the second character against '=' 1665: if (c1 == '=') ... 1678: value = ASSIGN; goto done; // Unread the next charcter if it didn't match. 1700: ungetc (c1, finput); "a +/* */= 1" wouldn't have parsed either, because /**/ are translated to spaces by the preprocessor. https://github.com/huangguiyang/gcc-0.9/blob/a83ea1b45dc3187d9fc4f7a3d8091c1454991afe/cccp.c#L974 https://github.com/huangguiyang/gcc-0.9/blob/a83ea1b45dc3187...*